It is generally known that CFRP skin shells can be reinforced with reinforcing elements (what are known as CFRP stringers) in order to withstand the high loads which occur in aircraft or spacecraft, with as little additional weight as possible. In this case, a distinction is basically made between two types of stringers: T-stringers and omega-stringers.
T-stringers have a narrow head portion and a wide foot portion. They are connected at the foot portion to the skin shell and, advantageously, can be produced in a simple manner.
Omega-stringers have an approximately hat-shaped profile, of which the ends are connected to the skin shell as a foot portion.
The use of fibre composite components is widespread within the aircraft industry. They are produced, for example, by vacuum infusion processes in order to introduce a matrix, for example an epoxy resin, into the fibre semi-finished products and are subsequently cured. Infusion processes may be more cost-effective than other known methods for producing fibre composite components, such as the prepreg process, since cheaper fibre semi-finished products may be used.
When producing shell components for the aircraft industry, it is thus currently imperative to use reinforcing stringers having different profile shapes. Owing to the requirement to withstand constant loading and the need to build the structures so as to be as light as possible, suitable for production and easy to service, it may be necessary to couple stringers, which may also have different profile shapes, at a transverse joint between shell elements to be connected to one another. In this case, problems may arise owing to the manufacturing tolerances of the components to be connected which, on the one hand, may lead to necessary further development and, on the other hand, to the need to also individually adjust the couplings.
The object of the present invention is therefore to provide a connection arrangement for reinforcing elements which overcomes the aforementioned drawbacks, or else considerably reduces them, and also presents further advantages.
A connection arrangement is accordingly provided for connecting a first and second reinforcing element of an aircraft or spacecraft. The reinforcing elements each have profiled cross-sections comprising at least one foot portion and at least one web portion and are spaced from one another at their end connection faces by a strap element. The connection arrangement comprises at least one foot portion connection element, which can be adjusted and firmly joined on one side to the geometrical shape of the foot portion of the first reinforcing element, on the other side to the geometrical shape of the foot portion of the second reinforcing element and to the interposed strap element. Furthermore, the connection arrangement comprises at least one web coupling element, which can be adjusted and firmly joined on one side to the geometrical shape of the web portion of the first reinforcing element, and on the other side to the strap element.
A shell component for an aircraft or spacecraft is also provided. It comprises at least two shell elements connected to a strip element at a transverse seam, said shell elements each comprising at least a first and second reinforcing element. The reinforcing elements each have profiled cross-sections comprising at least one foot portion and at least one web portion. These reinforcing elements are connected in their longitudinal direction by means of a connection arrangement and are spaced from one another at their end connection faces by the strap element. The connection arrangement is also connected to said strap element.
Advantageous developments and improvements of the present invention can be found in the dependent claims.
The invention is based on the idea of providing a connection arrangement comprising at least one foot portion connection element and one web coupling element, in which the foot portion connection element can be adjusted and firmly joined on one side to the geometrical shape of the foot portion of the first reinforcing element, on the other side to the geometrical shape of the foot portion of the second reinforcing element and to the interposed strap element, and the at least one web coupling element can be adjusted and firmly joined on one side to the geometrical shape of the web portion of the first reinforcing element, and on the other side to the strap element.
The present invention thus has the advantage, inter alia, over the aforementioned approaches that in one configuration it is possible to couple reinforcing elements across a transverse joint between two shell elements using a connection arrangement. In this case, foot portions of the reinforcing elements are connected to the interposed strap element by way of foot portion connection elements of the connection arrangement. Furthermore, the web portion of one of the reinforcing elements is coupled to the strap element independently of a foot portion connection element. The strap element connects the shell elements at the transverse joint and the connection arrangement is thus also connected to the shell elements via the strap element.
It is thus possible to compensate for manufacturing and assembly tolerances of the reinforcing elements by way of the connection, since the at least one foot portion connection element and the web coupling element are configured as what is known as a differential coupling and are not interconnected.
In a preferred embodiment, the connection arrangement can be divided into three individual components: two foot portion connection elements and one web coupling element arranged centrally therebetween. In this way, the connection arrangement elements may be produced in a highly variable and simplified manner. Any adjustments made when assembling the connection arrangement are reduced to a minimum. The foot portion connection elements and the web coupling element may, since they are not interconnected, be arranged in a transverse direction in such a way that there is space between them in the transverse direction for further joining elements, such as angle brackets for frames.
In another embodiment it is possible for reinforcing elements having different profiled cross-sections (the reinforcing elements may, for example, be configured as T-stringers and omega-stringers) to be coupled to the connection arrangement according to the invention across the transverse joint between the shell elements.
Furthermore, it is also possible to use the connection arrangement according to the invention where a longitudinal seam (longitudinal joint) of a shell element abuts a transverse seam (butt joint). The transverse seam is provided for coupling to the strap element (peripheral strip or butt strap) and the longitudinal seam is coupled by a strip element (longitudinal strap). A reinforcing element, for example a T-stringer, is arranged on the strip element and as a result of being fixed, for example riveted in place, also reinforces the longitudinal seam. The strip element may be widened in the region of the transverse joint. In this case a non-positive connection is formed with the foot portion of the reinforcing element. Furthermore, the join between a strap element and strip element can be connected by means of an additional cross-strap element which is also arranged between the end faces of the reinforcing elements.
The web coupling element can be adjusted and firmly joined on one side to the respective geometrical shape of the web portion and of the foot portion of the first reinforcing element, and on the other side to the strap element. This is enabled in a preferred embodiment in that the web coupling element comprises a web coupling portion for connection to the web portion of the first reinforcing element and a strap connection portion for connection to the strap element. The web coupling portion and the strap connection portion are preferably interconnected, for example in the manner of a T-shaped profile.
In an alternative embodiment, for example for higher loads, the web coupling element may also comprise, in addition to the web coupling portion m for connection to the web portion m of the first reinforcing element and in addition to the strap connection portion for connection to the strap element, a foot connection portion for connection to the foot portion of the first reinforcing element. It is thus preferable for the foot connection portion to comprise a recess for receiving the web portion of the first reinforcing element. The recess may be configured in such a way that the web portion, for example a portion of a web of a T-stringer, can be received. Other shapes are of course possible for different webs.
In order to ensure that the load is transferred smoothly and evenly, the free end of the web coupling portion of the web coupling element may be bevelled. The bevel may be at a predetermined angle, preferably between 15° and 45°.
In one embodiment, the foot portion connection elements are configured so as to have an L-shaped profile but may, for example, also comprise flat material or have a differently shaped profile. Since construction of the connection arrangement may vary independently of the web coupling elements, individual connections of stringer foot portions having the same or even different shapes of stringer profiles may be produced, independently of the profile shape. Consequently, it is not necessary to use a wide variety of parts even within a large field of application.
The foot portion connection element is preferably configured so as to have an L-shaped profile and, consequently, a cost-effective standard profile which can be cut to length and is of good quality may be used. Other profile shapes are of course conceivable. The foot portion connection elements, may, for example, be cut from the same profiled rod for both sides of the connection arrangement, no mirror-image embodiments being necessary.
In this case also, the free ends of the projecting arm of the foot portion connection element may each be bevelled so as to ensure that the load is transferred smoothly and evenly. This bevel may be at a predetermined angle, for example between 15° and 45°.
The free end of the second reinforcing element may also be bevelled. If the second reinforcing element is an omega-stringer for example, its free web end may be elliptically bevelled within the aforementioned angular ranges.
The foot portion connection element and the web coupling element may be made of metal or/and composite material, for example fibre composite material, or a combination thereof. They may be joined and connected, for example by rivets.
If made of metal, the height may be leveled directly in the connection region, for example between the strap elements and foot portions, by corresponding reinforcements joggles), shims not being necessary. If fibre composite materials are used, height is leveled using rigid spacers (shim plates).
It is preferable for at least one foot portion of the reinforcing elements to be widened at the connection site of the reinforcing elements. Consequently, a larger support surface is provided for the foot portion connection elements for an advantageously large load transfer and increased rigidity.
Rigidity may be adjusted in accordance with the application requirements and any lateral tolerance compensated for by mechanically trimming the elements of the connection arrangement.
A shell component may comprise the aforementioned connection arrangement.
In the figures, like reference numerals refer to like or functionally similar elements, unless otherwise indicated.